The NOI (extratropical-based Northern Oscillation Index) and its analog, the SOI (extratropical-bassed Southern Oscillation Index) are new indices of midlatitude climate fluctuations that show interesting relationships with fluctuations in marine ecosystems and populations. They reflect the variability in equatorial and extratropical teleconnections and represent a wide range of local and remote climate signals. The indices are counterparts to the traditional SOI (Southern Oscillation Index) that relate variability in the atmospheric forcing of climate change in northern and southern midlatitude hemisphere regions.